JP2005272931A - Method for reinforcing light alloy wheel for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for reinforcing a light alloy wheel at a low cost. <P>SOLUTION: In the light alloy wheel, a groove 14a linearly elongating to the radial direction of the wheel is formed on the back face (the face on the vehicle side) in a cross-link part 14 formed between troughs in a disk part. The regions 31 on both the sides of the groove 14a are modified, so as to be reinforced. Namely, a rotary tool 80 is applied to the back face of the cross-link part 14 while being rotated, and is moved along the groove 14a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for strengthening a light alloy wheel for a vehicle such as a cast aluminum wheel.

  Recently, a vehicle wheel made of a light alloy such as aluminum (including an aluminum alloy, the same applies hereinafter) has been developed. This wheel has an advantage that it can be manufactured with a light weight and a good appearance, but further weight reduction is required due to demands for improving the fuel efficiency and environmental impact of automobiles. In particular, in the case of a wheel obtained by casting, the strength is lower than that obtained by molding a forged product or a rolled material, and there is a strong demand for overcoming the strength problem for weight reduction (thinning).

In order to increase the strength of the light alloy wheel, it is necessary to make it thick overall, which contradicts the requirement for weight reduction. For this reason, only the part related to strength is made thick, and the other parts are thinned. In order to further reduce the weight, it is effective to reduce the thickness of the thick part between the disk part (particularly the bridging part or hub part) or the rim drop part of the rim part and the bead seat part. The strength of the part needs to be improved.
Also, special consideration is required for reinforcing the nut seat. More specifically, a plurality of bolt holes are formed in the disc portion of the wheel at intervals in the circumferential direction. A nut seat is formed so as to be connected to one end of the bolt hole. When attaching the wheel to the vehicle, insert the hub bolt into the bolt hole, screw the nut into this hub bolt, and tighten it toward the nut seat. When the wheel is a light alloy, the nut seat receives a tightening load from the nut and causes galling or the like, which causes a reduction in the mounting accuracy of the wheel. Therefore, in Patent Document 1, an aluminum wheel is insert-molded so as to incorporate a high-strength bush having a bolt hole and a nut seat.
JP 2002-293104 A Japanese Patent Laid-Open No. 10-183316

However, in the method disclosed in Patent Document 1, since the bush and the aluminum wheel base material are dissimilar metals, the problem of corrosion occurs, the recyclability is poor, and the manufacturing cost is high.
Patent Document 2 discloses a method of refining and strengthening a structure by softening a cast aluminum material by frictional heat from a rotary tool and stirring (plastic flow) in a solid state. ing. The present invention applies this technique to reinforce an aluminum wheel.

The present invention has been made to solve the above problems, and in one aspect thereof, in a method for reinforcing a light alloy wheel for a vehicle in which a plurality of decorative holes are formed at intervals in the circumferential direction of a disk portion, While rotating the rotary tool, with the tip of the rotary tool in contact with the surface of the disc part, the rotary tool is moved along at least a part of the periphery of each decorative hole, so that the region on the movement trajectory is frictionally heated. And is made to flow in the solid phase, thereby reforming the region on the movement trajectory.
According to this method, at least a part of the periphery of the decorative hole can be reformed and strengthened at low cost, and thickening of the disk portion can be avoided.

In another aspect of the present invention, in a method for strengthening a light alloy wheel for a vehicle in which a plurality of decorative holes are formed at intervals in the circumferential direction of the disk portion and a bridging portion is disposed between the decorative holes, While rotating the tool, the region on the movement trajectory is softened by frictional heat and the solid phase is moved by moving the rotating tool in the radial direction of the wheel while the tip is in contact with the surface of the bridge portion. It is made to flow in a state, and thereby the bridge portion is modified.
According to this method, the cross-linked portion can be modified and strengthened at low cost, and thickening of the cross-linked portion can be avoided.

  Preferably, a straight groove extending in the radial direction of the wheel is formed in the bridging portion, and the movement locus is set along both sides of the groove. Thereby, the intensity | strength of the bridge | crosslinking part in which the groove | channel is formed can be raised, and the thickening can be avoided.

In still another aspect of the present invention, the vehicle includes a disk portion and a rim portion, and the rim portion has an annular thickness suddenly changing portion formed at the boundary between the disk portion side bead seat portion and the rim drop portion. In the light alloy wheel strengthening method, the rotating tool is moved over the entire circumference of the sudden thickness change portion while rotating the rotary tool while the tip of the rotary tool is in contact with the vicinity of the sudden thickness change portion in the rim drop portion. Thus, the vicinity of the sudden thickness change portion is softened by frictional heat and stirred in the solid phase, thereby modifying the annular region near the sudden thickness change portion.
According to this method, it is possible to modify and strengthen the vicinity of the sudden thickness change portion where stress is concentrated at low cost, and to avoid the increase in thickness.

In still another aspect of the present invention, a plurality of bolt holes for inserting hub bolts are formed at intervals in the circumferential direction of the disk portion, and nuts screwed into the hub bolts are connected to one end of the bolt holes. In a method for strengthening a light alloy wheel for a vehicle on which a nut seat for receiving is formed, the processed portion is applied to the nut seat while rotating a rotary tool having a surface-shaped processed portion corresponding to the nut seat. Thus, the nut seat is softened by frictional heat and is allowed to flow in a solid state, whereby the nut seat is reformed.
According to this method, the mounting accuracy of the wheel can be ensured by modifying and strengthening the nut seat. In addition, the nut seat can be modified and strengthened at a low cost without using dissimilar metals.

In still another aspect of the present invention, in a method for strengthening a light alloy wheel for a vehicle in which a plurality of bolt holes for inserting hub bolts are formed at intervals in the circumferential direction of the disk portion, while rotating a rotary tool, With the tip part in contact with the surface of the disk part, the rotary tool is moved along the annular area concentric with the bolt hole surrounding each bolt hole, so that the annular area is softened by frictional heat. At the same time, it is made to flow in a solid phase state, thereby reforming the annular region.
According to this method, the peripheral portion of the bolt hole that receives a large load can be modified and strengthened at a low cost, and thickening of the disk portion can be avoided.

In still another aspect of the present invention, a plurality of bolt holes for inserting hub bolts are formed at intervals in the circumferential direction of the disk portion, and nuts screwed into the hub bolts are connected to one end of the bolt holes. In a method of strengthening a light alloy wheel for a vehicle in which a nut seat for receiving is formed, the nut seat is softened by frictional heat and is kept in a solid state by rotating the rotary tool against the nut seat. In this state, the nut tool is reformed, and the rotating tool is rotated, and the rotating tool is inserted into each bolt hole in a state where the tip of the rotating tool is in contact with the surface of the disk portion opposite to the nut seat. By moving along the annular region concentric with the surrounding bolt hole, the annular region is softened by frictional heat and allowed to flow in a solid state. Wherein the more performing modification of the annular region.
According to this method, the mounting accuracy of the wheel can be ensured by modifying and strengthening the nut seat. In addition, the nut seat can be modified and strengthened at a low cost without using dissimilar metals. Further, since the periphery of the bolt hole is modified and strengthened on both sides of the disk portion, the periphery of the bolt hole having a large load can be further strengthened, and the increase in thickness of the disk portion can be avoided.

In still another aspect of the present invention, in a method for strengthening a light alloy wheel for a vehicle in which a plurality of bolt holes for inserting hub bolts are formed at intervals in the circumferential direction of the disk portion, while rotating a rotary tool, The annular region is softened by frictional heat by moving the rotary tool along an annular region concentric with the wheel surrounding the plurality of bolt holes in a state where the tip portion is in contact with the surface of the disk portion. At the same time, it is made to flow in a solid phase state, thereby reforming the annular region.
According to this method, the annular region surrounding the plurality of bolt holes can be reformed and strengthened at low cost, and the thickening of the disk portion can be avoided.

  According to the present invention, in a light alloy wheel, a portion with a large load burden and a portion where stress is concentrated can be selectively reformed and strengthened at a low cost, and an increase in thickness can be avoided. Further, the mounting accuracy of the wheel can be improved by improving the nut seat.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 to 3, a cast aluminum wheel A (light alloy wheel) for a vehicle includes a disk portion 10 and a substantially cylindrical rim portion that extends toward the vehicle side and continues to the outer peripheral edge of the disk portion 10. 20.

  The disk portion 10 includes a hub hole 11 formed in the center, and a plurality of (four in the present embodiment) bolt holes 12 formed around the hub hole 11 at equal intervals in the circumferential direction. A plurality of (eight in the case of this embodiment) decorative holes 13 formed at equal intervals in the circumferential direction on the outer side of the bolt hole 12 (the outer side in the radial direction of the wheel A). A space between the decorative holes 13 is a bridging portion 14 extending linearly in the radial direction of the wheel A. As shown in FIG. 2, a straight groove 14 a for stealing meat extending in the longitudinal direction of the bridge portion 14 (the radial direction of the wheel) is formed on the back side (vehicle side) surface of the bridge portion 14. .

  As shown in FIG. 4, a conical nut seat 16 is formed on the front side (opposite side of the vehicle) end of the bolt hole 12. The hub of the axle is inserted into the hub hole 11 of the disk portion 10. Further, as shown in FIG. 4, a plurality of hub bolts 51 (bolts provided on the mounting flange portion 50 projecting in the radial direction from the outer periphery of the hub and projecting in the axle direction) are inserted into the bolt holes 12 of the disk portion 10 with play. A plurality of nuts 55 screwed into the end portions of the bolts 51 are fastened to the nut seat 16. Thereby, the wheel A is fixed to the axle. The nut 55 has a conical surface 55a having an inclination angle equal to that of the nut seat 16, and the wheel A is firmly fixed when the conical surface 55a hits the nut seat 16 with a strong force.

  As shown in FIG. 3, the rim portion 20 includes a flange portion 21 on the disc portion 10 side, a bead seat portion 22, a rim drop portion 23, a bead seat portion 24 on the opposite side (vehicle side) of the disc portion 10, and a flange portion. 25 in series. The rim drop 23 has a small thickness and a small diameter with respect to the bead sheet 22, and the border is a sudden thickness change portion 29.

  In the wheel A having the above-described configuration, a linear region 31 (a part of the periphery of the decorative hole 13) located on both sides of the groove 14a of each bridging portion 14 is provided on the back side (vehicle side) surface of the disc portion 10; The circular annular region 32 concentric with the bolt holes 12 surrounding each bolt hole 12 and the annular region 33 concentric with the wheel A surrounding the plurality of bolt holes 12 are subjected to a modification process for refining and densifying the structure. Yes. Further, in the rim drop portion 23, the annular region 34 in the vicinity of the sudden thickness change portion 29 is also subjected to a modification process. Further, in the disk portion 10, the nut seat 16 is also subjected to a modification process for making the structure finer and denser.

  Next, the modification process for each region according to the present invention will be described in detail. A rotating tool 80 shown in FIG. 5 is used for the modification treatment of the regions 31 on both sides of the groove 14a of the bridging portion 14. The rotary tool 80 includes a cylindrical portion 81 having a flat lower end surface (tip surface) and a protrusion 82 formed at the center of the lower end surface of the cylindrical portion 81. The wheel A is positioned with the back side surface (vehicle side surface) of the disk unit 10 facing up, the rotary tool 80 is rotated, and the protrusion 82 is pressed against the back side surface of the bridging unit 14 to thereby generate frictional heat. Thus, the material is softened to allow the protrusion 82 to enter the bridging portion 14 by about 1 to 2 mm, and the lower end surface of the cylindrical portion 81 is pressed against the surface of the bridging portion 14. By moving the rotary tool 80 in the radial direction of the wheel A in this state, the region 31 is softened by frictional heat and fluidized in a solid state and rapidly cooled in the atmosphere. As a result, in the region 31, the crystal grains are refined, the structure is densified, casting defects such as pores are eliminated, and the strength is increased.

  In the case of the wheel A having the decoration hole 13, the load concentrates on the bridging portion 14 positioned therebetween, but the strength of the bridging portion 14 can be increased by the modification treatment of the region 31. Moreover, although the groove 14a is formed in the bridging portion 14, the strength of the bridging portion 14 can be secured.

  Using the rotary tool 80 or a similar rotary tool, the annular regions 32 and 33 are modified. That is, the annular region 32 is reformed by rotating the rotary tool 80 and rotating the bolt hole 12 in a circular shape while pressing it against the surface on the back side of the disk portion 10. The circular region 33 is modified by making one round so as to draw a circle around.

  In addition, the wheel A is mounted on the outer periphery of a mandrel (not shown), and the tip of the rotary tool or similar rotary tool is pressed near the sudden thickness change portion 29 in the rim drop portion 23 of the rim portion 20. The annular region 34 in the vicinity of the sudden thickness change portion 29 can be modified and strengthened by rotating the mandrel while rotating (spinning) the rotary tool 80. The annular region 24 is a portion where stress is concentrated. However, by increasing the strength, the annular region 24 can withstand the stress concentration without increasing the thickness.

  Next, the modification process of the nut seat 16 will be described. For this reforming process, a rotary tool 60 (first rotary tool) shown in FIGS. 6 and 7 is used. The rotary tool 60 is arranged vertically and has a columnar base 61, a processing portion 62 that is continuous with the tip (lower end) of the base 61, and an insertion portion 63 that is continuous with the tip of the processing portion 62. . The outer peripheral surface of the processed portion 62 forms a conical surface processing surface having the same inclination angle of the nut seat 16 described above.

  As shown in FIG. 7, the wheel A is set on the chuck base 70 with the nut seat 16 facing upward, for example. In this state, the rotary tool 60 is lowered from above, and the processed portion 62 is pressed against the nut seat 16 while rotating in a state where the posture is coaxial with the bolt hole 12 and the nut seat 16. As a result, the nut seat 16 is softened by frictional heat and plastically flows in the solid state. Then, by raising the rotary tool 60, the nut seat 16 is rapidly cooled in the atmosphere. As a result, in the nut seat 16, the crystal grains are refined, the structure is densified, casting defects such as pores are eliminated, and the strength is increased. In the present embodiment, the insertion portion 63 of the rotary tool 60 fits snugly into the bolt hole 12 to suppress the generation of burrs.

Since the strength of the nut seat 16 can be increased as described above, even if the nut 55 is tightened with a strong force when the wheel A is fixed, no twisting or the like occurs and the wheel A can be attached with high accuracy.
The modification process of the plurality of nut seats 16 may be performed at once by the plurality of rotary tools 60 or may be sequentially performed by the single rotary tool 60.
When burrs are generated in the above reforming process and the nut seat 16 is retracted from before the reforming process, it is sufficient to make it thicker by the retreat allowance.
The insertion part 63 of the rotary tool 60 has a cylindrical surface shape whose outer diameter is slightly larger than the inner diameter of the bolt hole 12, and at the same time as the modification of the nut seat 16, the inner peripheral surface of the bolt hole 12 is formed by the insertion part 63. A modification treatment may be performed.
Note that the modification process of the bolt hole 12 may be performed in a separate process from the modification process of the nut seat 16. In this case, a rotary tool having a cylindrical surface slightly larger in diameter than the bolt hole 12 is used and inserted into the bolt hole 12 while rotating.

  In addition, it is preferable that the modification depth in each of the above regions is 20% or more of the wall thickness. This is because the impact resistance is greatly improved.

The present invention is not limited to the above embodiment, and various aspects can be adopted.
A U-shaped region along the substantially entire length of the periphery of the decorative hole 13 in the disk portion 10 may be modified.
A rotary tool that modifies the nut seat 16 and a rotary tool that modifies other regions may be shared.
When the nut seat 16 is reformed, a rotary tool 60 ′ shown in FIG. 8 may be used. The rotary tool 60 ′ is substantially the same as the rotary tool 60 described above, and the corresponding components are given the same numbers, but an annular protrusion 62 a is formed on the outer peripheral surface of the processing portion 62. The annular protrusion 62a enters the nut seat 16 and enhances the stirring effect when the outer peripheral surface of the processed portion 62 hits the nut seat 16.
When the nut seat is not a conical shape but an annular flat surface orthogonal to the bolt hole, the processing surface of the rotary tool is an annular flat surface.

It is the figure which looked at the upper half of the aluminum wheel which applies the method of the present invention from the front side. It is the figure which looked at the upper half of the aluminum wheel from the back side. It is sectional drawing of the rim | limb part of the same aluminum wheel. It is a principal part expanded sectional view which shows the state which fixed the aluminum wheel to the hub. It is sectional drawing which shows the state which is carrying out the modification process of the bridge | crosslinking part of the aluminum wheel. It is a perspective view of the rotary tool used for the modification process of the nut seat of the aluminum wheel. It is a principal part expanded sectional view which shows the state which is modifying the nut seat using the rotary tool. It is a perspective view which shows the other aspect of the rotary tool used for the modification | reformation process of a nut seat.

Explanation of symbols

A Aluminum wheel (light alloy wheel)
DESCRIPTION OF SYMBOLS 10 Disc part 12 Bolt hole 13 Decoration hole 14 Bridging part 14a Groove 16 Nut seat 20 Rim part 22 Bead sheet | seat part 23 Rim drop part 29 Thickness sudden change part 31-34 Modified area | region 60,60 'Rotary tool 62 Processing part 80 Rotary tool

Claims (8)

In the method of strengthening a light alloy wheel for a vehicle in which a plurality of decorative holes are formed at intervals in the circumferential direction of the disk portion,
While rotating the rotary tool, with the tip of the rotary tool in contact with the surface of the disc part, the rotary tool is moved along at least a part of the periphery of each decorative hole, so that the region on the movement trajectory is frictionally heated. A method for strengthening a light alloy wheel for a vehicle, characterized in that the region of the moving locus is reformed by being softened by a fluid and flowing in a solid state. In the method of strengthening a light alloy wheel for a vehicle in which a plurality of decorative holes are formed at intervals in the circumferential direction of the disk portion and a bridging portion is disposed between the decorative holes,
The rotating tool is moved in the radial direction of the wheel while the tip of the rotating tool is in contact with the surface of the bridging portion while rotating the rotating tool. A method for strengthening a light alloy wheel for a vehicle, characterized by flowing in a phase state and thereby modifying the bridge portion.   The light alloy wheel for a vehicle according to claim 2, wherein a linear groove extending in a radial direction of the wheel is formed in the bridging portion, and the movement locus is set along both sides of the groove. How to strengthen. In the method of strengthening a light alloy wheel for a vehicle, comprising a disk part and a rim part, and an annular thickness suddenly changing part is formed at the boundary between the disk part side bead seat part and the rim drop part on the rim part,
While rotating the rotary tool, the tip of the rim drop part is in the vicinity of the sudden thickness change part in the rim drop part, and the rotary tool is moved over the entire circumference of the sudden thickness change part. A method for strengthening a light alloy wheel for a vehicle, comprising: softening with frictional heat and stirring in a solid state, thereby reforming an annular region in the vicinity of the sudden thickness change portion. A plurality of bolt holes for inserting hub bolts are formed at intervals in the circumferential direction of the disk portion, and a nut seat for receiving a nut screwed to the hub bolt is formed so as to be connected to one end of the bolt hole. In a method for strengthening a vehicle light alloy wheel,
While rotating a rotary tool having a surface-shaped machining portion corresponding to the nut seat, by applying the machining portion to the nut seat, the nut seat is softened by frictional heat and flows in a solid state, A method for strengthening a light alloy wheel for a vehicle, characterized in that the nut seat is reformed. In a method for strengthening a light alloy wheel for a vehicle in which a plurality of bolt holes for inserting hub bolts are formed at intervals in the circumferential direction of the disk portion,
While rotating the rotary tool, with the front end of the rotary tool in contact with the surface of the disk part, the rotary tool is moved along an annular area concentric with the bolt hole surrounding each bolt hole. A method for strengthening a light alloy wheel for a vehicle, characterized in that the vehicle is softened by frictional heat and is allowed to flow in a solid state, thereby modifying the annular region. A plurality of bolt holes for inserting hub bolts are formed at intervals in the circumferential direction of the disk portion, and a nut seat for receiving a nut screwed to the hub bolt is formed so as to be connected to one end of the bolt hole. In a method for strengthening a vehicle light alloy wheel,
By rotating the rotary tool against the nut seat, the nut seat is softened by frictional heat and flowed in the solid state, thereby modifying the nut seat and rotating the rotary tool. By moving the rotary tool along an annular region concentric with the bolt hole surrounding each bolt hole in a state where the tip portion is in contact with the surface of the disk portion opposite to the nut seat, A method for strengthening a light alloy wheel for a vehicle, characterized in that the region is softened by frictional heat and is allowed to flow in a solid state, thereby reforming the annular region. In a method for strengthening a light alloy wheel for a vehicle in which a plurality of bolt holes for inserting hub bolts are formed at intervals in the circumferential direction of the disk portion,
While rotating the rotary tool, with the leading end of the rotary tool being in contact with the surface of the disk part, the rotary tool is moved along an annular area concentric with the wheel surrounding the plurality of bolt holes. A method of strengthening a light alloy wheel for a vehicle, characterized by softening with frictional heat and flowing in a solid state, thereby modifying the annular region.

Images